What is recommend variety of serviceberry to plan in Baltimore City? Ideally, I want one that is more tree-like and gets good berries. From local nurseries, I have options of common serviceberry (Amelanchier arborea) and smooth serviceberry (Amelanchier laevis).
Serviceberry species/varieties can vary a bit in appearance depending on how they were grown at the nursery. Some can be tree-like if trained to have a single leader and no suckers; others will be shrub-like with multiple trunks and low branching. There isn't much information available on best-tasting fruit (if you intend to harvest them), but otherwise, several should be equally good to try. Similarly, Serviceberries in general can be susceptible to a fungus disease called rust and sap-sucking insects called lace bugs, but pests and diseases tend to be weather-dependent and can afflict stressed plants more than healthy vigorous ones.
According to the MD Biodiversity Project, there are three species of Amelanchier that occur fairly widely in the state that are also the species possible to find at nurseries: A. arborea, A. canadensis, and A. laevis. https://www.marylandbiodiversity.com/viewChecklist.php?genus=Amelanchier The hybrid A. x grandiflora is also on the market and is a hybrid between arborea and laevis. Cultivars exist for several of these species. Unless specific cultivars claim to have an increased resistance to rust, we do not have specific suggestions as to type. Rust can ruin the fruit on Amelanchier for that season, though the disease is otherwise not typically greatly damaging to this tree. Spores need an alternate host for part of the year (our native Eastern Redcedar juniper) and if this is not located close enough to the trees, infection is less likely. https://extension.umd.edu/hgic/topics/rust-diseases-trees